We have the same model but a 2014. We thought the same thing. When we have someone sleep there we roll up a blanket to put into that spot. Someone didn't think that through.
We also bought foam for the middle section. My question is do you folks leave it in the middle all of the time or do you take the foam out when the bed is not in use? Also, we have a bed above the cab and when the sofa bed is out you cannot use the ladder for the bed above the cab.
I'm sure you're setting it up correctly there is a support bar that pulls down underneath the bed you have to look very closely...
that will prevented from sagging